The invention relates generally to sensors. The invention particularly relates to magneto-optical current and magnetic field sensors.
Conventional transformer-based current sensors are large in size for field operations and tend to saturate at high voltages or currents. Alternative current sensors, such as optical current sensors, typically rely upon the Faraday effect of the magnetic field created by the current to alter the polarization of light propagating in a fiber near the conductor. The method for extracting this information from the fiber is very intricate and costly. In one example, complex active power supplies are located at line potential. Fiber-optic current sensors based on polarimetric methods require stringent control on the polarization state. The components for polarization measurement are usually based on costly bulk optical components and maintaining the alignment through a number of these types of components becomes a challenging task. Furthermore, cascading polarimetric current sensors for distributed sensing applications may not be practical due to system complexity.
Measurement of currents flowing in high-voltage environments is also highly desirable, especially in power transmission and distribution systems. Transmission and distribution systems react dynamically to changes in active and reactive power. For power transmission to be economical and the risk of power system failure to be low, reactive compensation systems are desirable, particularly systems capable of simultaneously monitoring current flow at several points on a grid.
There is a need therefore for low cost current metering and instrumentation. There is a particular need for a current measuring system that allows for multiplexing, which can be economically scaled and used in applications where instrumentation of multiple channels is required.